Support 'Conditional' idl attribute.

client/dom/generated/src/interface/HTMLContentElement.dart

Index: client/dom/generated/src/interface/HTMLContentElement.dart
diff --git a/client/dom/generated/src/interface/HTMLContentElement.dart b/client/dom/generated/src/interface/HTMLContentElement.dart
deleted file mode 100644
index 6031aec36f3a2a2599b516aebc3e3dc888cdca77..0000000000000000000000000000000000000000
--- a/client/dom/generated/src/interface/HTMLContentElement.dart
+++ /dev/null
@@ -1,12 +0,0 @@
-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-// WARNING: Do not edit - generated code.
-
-interface HTMLContentElement extends HTMLElement {
-
-  String get select();
-
-  void set select(String value);
-}